Seismic Loss Estimation Research Articles

Impact of parameter selection on seismic loss and recovery time estimates: A variance-based sensitivity analysis

Probabilistic models in performance-based earthquake engineering propagate uncertainties from key input parameters to output performance measures. Although these models integrate important sources of uncertainty, several model parameters are deterministic and remain constant despite the difficulty in defining them with high confidence based on empirical or theoretical arguments. This study employs variance-based sensitivity analysis to investigate how uncertainty in (1) demands, (2) fragility functions, (3) building replacement consequences and (4) impeding factor delays impact seismic loss and recovery time estimates. The results indicate that the size of modeling uncertainty added to the simulated demand distribution has the most significant impact on the variance in seismic losses at all, but the highest hazard level, that is, 2475-year. At low hazard levels, that is, 100 and 475 years, the uncertainty in the capacity of structural components (e.g. slab–column connections) and nonstructural components (e.g. elevator) are the main contributors to variance in downtime to re-occupancy and functional recovery, respectively. At the 2475-year intensity level, the uncertainty in building replacement cost and replacement time becomes the primary contributor of the variance in the seismic loss and recovery time outputs due to the high probability of irreparable damage. The analyses presented in this article offer valuable insights into which parameters deserve more attention when conducting seismic loss and recovery time assessments.

Influence of acceleration-sensitive non-structural element classification on seismic loss estimation of a case-study building in Italy

Influence of acceleration-sensitive non-structural element classification on seismic loss estimation of a case-study building in Italy

A semantic augmented approach to FEMA P-58 based dynamic regional seismic loss estimation application

A semantic augmented approach to FEMA P-58 based dynamic regional seismic loss estimation application

Assessment of seismic potential impacts of an Mw 8.4 hypothetical earthquake in central Nepal province

Assessment of seismic potential impacts of an Mw 8.4 hypothetical earthquake in central Nepal province

Assessing the Impact of Ground Motion Duration on Losses in Typical Modern Steel Moment Frames

This research was undertaken to study the duration effects on the seismic economic risk of steel moment frame (SMF) buildings, a prominent class of buildings in commercial stock. Firstly, a modified version of FEMA P-695 ground motion scaling, tailored for seismic loss estimation purposes and incorporating two sets of spectrally matched bi-directional short- and long-duration ground motions, is proposed to study code-compliant plan-symmetrical SMFs with different heights (i.e., two to 20 stories). It is shown that long-duration ground motions increase the collapse risk of SMFs, on average, by 28.0% at the MCE level. Next, a component-based loss estimation methodology was adopted for evaluating the seismic losses under each set of ground motions. These losses are studied separately for building components (i.e., structural and nonstructural) and contents. Moreover, we propose an approach for calculating average annualized loss (AAL) as a prominent risk meter that segregates contributions of short- and long-duration ground motions to attain hazard consistency. Loss analyses showed the minimal impact of building height on the contribution of these two types of earthquakes. The seismic risk analysis of buildings also revealed that collapse risk is influenced mainly by duration effects followed by building and content losses.

Influence of local versus national datasets on seismic loss estimates: A case study for residential buildings in the metropolitan area of Montreal, Canada

Influence of local versus national datasets on seismic loss estimates: A case study for residential buildings in the metropolitan area of Montreal, Canada

Consequences of consequence models: The impact of economies of scale on seismic loss estimates

The detailed evaluation of expected losses and damage experienced by structural and nonstructural components is a fundamental part of performance-based seismic design and assessment. The FEMA P-58 methodology represents the state of the art in this area. Increasing interest in improving structural performance and community resilience has led to widespread adoption of this methodology and the library of component models published with it. This study focuses on the modeling of economies of scale for repair cost calculation and specifically highlights the lack of a definition for aggregate damage, a quantity with considerable influence on the component repair costs. The article illustrates the highly variable and often substantial impact of damage aggregation that can alter total repair costs by more than 25%. Four so-called edge cases representing different damage aggregation methods are introduced to investigate which components experience large differences in their repair costs and under what circumstances. A three-step evaluation strategy is proposed that allows engineers to quickly evaluate the potential impact of damage aggregation on a specific performance assessment. This helps users of currently available assessment tools to recognize and communicate this uncertainty even when the tools they use only support one particular damage aggregation method. A case study of a 9-story building illustrates the proposed strategy and the impact of this ambiguity on the performance of a realistic structure. The article concludes with concrete recommendations toward the development of a more sophisticated model for repair consequence calculation.

Evaluating the impact of parametric pushover curve model uncertainties on seismic loss estimation for a specific building stock in Slovenia

Evaluating the impact of parametric pushover curve model uncertainties on seismic loss estimation for a specific building stock in Slovenia

Seismic performance evaluation of reinforced concrete hilly buildings under sequence of earthquakes

SummaryThe present study investigates the effect of earthquake sequences on the response of reinforced concrete hilly buildings having typical configurations, that is, stepback and split‐foundation, with three different story ratios. A set of 30 as‐recorded mainshock‐aftershock sequence of earthquake ground motions is considered for this study. Mainshock acceleration time histories are scaled at two distinct intensity levels to obtain the mainshock‐damaged building. These mainshock‐damaged hilly buildings are then subjected to aftershocks. A comparative study is performed for various response quantities, such as peak interstory drift ratio, peak floor acceleration, and peak roof displacement of undamaged and mainshock‐damaged buildings under aftershocks. Further, fragility analysis is carried out to study the effect of aftershocks on undamaged and mainshock‐damaged hilly buildings. Subsequently, component‐wise seismic loss estimation due to damage in the non‐structural and structural components is performed. It is concluded from the study that the building components that contribute maximum to the expected repair cost ratio vary with respect to the intensity of the aftershocks. Also, the estimated seismic loss is higher in mainshock‐damaged split‐foundation buildings in comparison to stepback buildings.

Machine vision‐based automated earthquake‐induced drift ratio quantification for reinforced concrete columns

SummaryThis paper presents a novel method for estimating the seismic peak interstory drift ratio (IDR) in reinforced concrete (RC) columns after an earthquake using surface crack image analysis. The quantitative representation of the complexity and irregularity of crack images in damaged RC columns is obtained through the consideration of the generalized fractal dimensions. The authors have compiled a comprehensive database consisting of 445 crack maps obtained from cyclic experiments conducted on 110 rectangular RC column specimens exhibiting double‐curvature deformation mode. This database is utilized by the authors to develop and validate the proposed procedure. The research database contains a wide range of structural and geometric features. Five closed‐form equations are developed with the objective of estimating the peak IDR experienced by the RC columns during a seismic event. The predictive equations are derived through the utilization of symbolic regression technique, with the input parameters varying according to the availability of columns characteristic parameters. Results reveal that generalized fractal dimensions, especially D−1, are strong vision‐based indicator of damage in RC columns having correlation coefficients with IDR ranging from 0.82 to 0.92 across the considered plans. The seismic peak IDR obtained through the empirical equations can serve as the input engineering demand parameter (EDP) in the seismic loss estimation frameworks. This allows for the determination of the probability of exceeding damage states for structural and nonstructural components of concrete buildings. Finally, the practical implementation of the methodology is examined by its application to an actual case of a damaged column during the Kermanshah earthquake of magnitude 7.3 that occurred in 2017.

Seismic risk assessment of ageing existing reinforced concrete bridges accounting for uncertainty in bearing properties

Seismic risk assessment of ageing existing reinforced concrete bridges accounting for uncertainty in bearing properties

Regional seismic loss estimation and critical earthquake scenarios for the Western Quebec seismic zone

ABSTRACT Earthquakes pose potentially substantial risks to residents in the Western Quebec seismic zone of eastern Canada, where Ottawa and Montreal are located. In eastern Canada, the majority of houses are not constructed to modern seismic standards and most homeowners do not purchase earthquake insurance for their homes. If a devastating earthquake strikes, homeowners would be left unprotected financially. To quantify financial risks to homeowners in the Western Quebec seismic zone, regional earthquake catastrophe models are developed by incorporating up-to-date public information on hazard, exposure and vulnerability. The developed catastrophe models can quantify the expected and upper-tail financial seismic risks by considering a comprehensive list of possible seismic events as well as critical earthquake scenarios based on the latest geological data in the region. The results indicate that regional seismic losses could reach several tens of billions of dollars if a moderate-to-large earthquake occurs near urban centres in the region, such as Montreal and Ottawa. The regional seismic loss estimates produced in this study are useful for informing earthquake risk management strategies, including earthquake insurance and disaster relief policies.

Simplified Procedure for Rapidly Estimating Inelastic Responses of Numerous High-Rise Buildings with Reinforced Concrete Shear Walls

Nonlinear response history analysis (NLRHA) is considered the most accurate procedure for evaluating the seismic performance of high-rise buildings. However, it requires considerable expertise and analysis time, making it inappropriate for some applications involving numerous high-rise buildings (e.g., the seismic loss estimation of a city). To overcome this limitation, a simplified procedure developed based on the uncoupled modal response history analysis (UMRHA) and coupled shear-flexural cantilever beam model (CSFCBM) is proposed. The underlying assumption is that the UMRHA procedure can compute the nonlinear seismic responses mode by mode, where each vibration mode is assumed to behave as a single-degree-of-freedom system. The nonlinear seismic responses are approximately represented by the sum of the modal responses of a few vibration modes. However, UMRHA requires knowledge of the modal properties and modal hysteretic behaviors. Therefore, the CSFCBM was introduced here to estimate the required modal properties and modal hysteretic behaviors. The inelastic seismic demands of the building can be determined using the UMRHA procedure with the computed modal properties obtained by CSFCBM. The accuracy of this proposed procedure was verified considering four high-rise buildings of 19, 30, 34, and 45 stories with reinforced concrete shear walls. The inelastic demands computed by the NLRHA procedure were used as a benchmark and compared with those of the proposed procedure. The results indicate that the proposed procedure provides reasonably accurate demand estimations for all case study buildings. Additionally, the total calculation time for modeling one building, performing dynamic analysis on 24 cases of ground motions, and post-processing the results required by the proposed procedure was about 7 to 45 times lower than that of the NLRHA procedure. Therefore, it can be used for estimating the seismic damage and losses of many high-rise buildings in a city for a specific earthquake scenario or a quick assessment of various seismic design options of a high-rise building in the preliminary design phase.

Spatially correlated Vs30 estimation in the Beijing area

Beijing is an international metropolis, that is also an earthquake-prone city. The aims of this study are detailed quantifying and qualifying soil layer properties for an accurate seismic safety evaluation in the Beijing area. The time average shear-wave velocity in the first 30 m of subsoil, Vs30, is an important site parameter used in site response analysis, site classification, and seismic loss estimation. Mapping of Vs30over a city-scaled region is commonly done through proxy-based methods by correlating Vs30with geological or topographic information. In this paper, a geostatistical-based random field model is presented and applied to mapping Vs30over extended areas. This random field model is then coupled with Monte Carlo simulations to obtain an averaged Vs30map and its associated uncertainties. Unlike the traditional deterministic prediction model, this framework accounts for spatial variations of Vs30values and uncertainties, which makes the prediction more reliable. A total of 388 shear wave velocity measurements in the Beijing area are used to calculate Vs30values, from which the statistical and spatial properties for the random field realizations are inferred. New spatially correlated probabilistic Vs30maps for the Beijing area are then represented, and the effect of the maximum number of previously generated elements to correlate to in estimating Vs30maps is tested.

Lifetime seismic risk assessment of bridges with construction and aging considerations

The seismic risk analysis of bridges in the construction period has not drawn due attention in the seismic risk assessment of the whole bridge life cycle. Therefore, a seismic risk framework, including the bridge construction period, was developed to complete the full bridge life-cycle seismic risk analysis. A case study of this newly developed framework based on a continuous beam bridge considering different construction methods was conducted for life-cycle seismic risk analysis, where the material aging factor during the operation period was also incorporated. This two-stage seismic risk analysis integrating the construction and operation stages of bridges could provide a complete understanding of the seismic risk of the whole bridge life cycle. It also enables the quantification of the impact of factors like atmospheric environment, seismic intensity, multiple earthquakes, and construction methods through the whole life-cycle seismic loss estimation. The construction stage was found to account for 5% or more in the whole life-cycle seismic loss, which could be significantly reduced by selecting construction methods that result in the least seismic risk during construction.

Infill Variability and Modelling Uncertainty Implications on the Seismic Loss Assessment of an Existing RC Italian School Building

Past earthquake evidence has shown the high vulnerability of Italian school buildings, given by the extensive damage observed to structural and non-structural elements. Such vulnerability demonstrates the need to undertake a seismic risk assessment and reduction strategies for critical facilities and allocation of national funds for retrofit interventions to those regions where seismic risk is higher. To do so, Expected Annual Losses (EAL) are evermore considered one of the main seismic risk metrics, which can, however, be largely affected by the epistemic uncertainty that typically characterizes the material and geometrical properties of existing buildings, particularly masonry-infilled reinforced concrete (RC) ones. This paper investigates the implications of accounting for a thorough identification of sources and characterization of uncertainty in seismic loss estimates on the risk assessment of a typical Italian masonry-infilled RC school building. The variability in masonry infill properties and modeling assumptions, as well as the subsequent epistemic uncertainty, are explicitly considered in the loss estimation of the RC school building. Specifically, the impact on the expected annual loss ratio is quantified in terms of both structural and non-structural components, depending on the engineering demand parameter to which they are sensitive. The results show that, when considering the uncertainty related to the variability in masonry infills, higher loss ratios of up to 30% are obtained with respect to the available literature estimates.

Impact of local site effects on seismic risk assessment of reinforced concrete bridges

In most practical applications of performance-based earthquake engineering, the local site characteristics are considered simplistically, and soil-structure interaction effects are ignored. Within such a conventional approach, the ground motion record selection uses the time-averaged shear-wave velocity in the top 30 m of the soil profile ( V S30 ) as the main proxy to represent the site where the structure is located. This study aims to assess the impact of local site effects on the risk assessment of reinforced concrete ( RC ) bridges by incorporating the local-site response and soil-structure interaction effects more realistically within a more detailed approach. For this purpose, seismic risk assessment of RC bridge structures with various configurations located on varying site characteristics was carried out using different levels of refinement in the numerical modelling. Local site amplification was incorporated using site response analysis, and p-y models were used to consider foundation flexibility. Cloud analyses were then carried out on both modelling approaches to obtain and compare the corresponding scenario-based seismic loss estimates for the structures. Moreover, the results of numerical analyses were scrutinized in terms of peak demand to capacity ratio values, and statistical hypothesis testing was used to quantify the similarity between the two approaches further. In some cases of site response modeling, especially when the fundamental periods of the bridge structure and site are sufficiently close, higher displacement demands on bridge piers were obtained, likely leading to higher direct seismic losses. • Scenario-based seismic risk assessment of reinforced concrete bridges is performed. • Local site effects are taken into account with different approaches. • Site response analyses are performed, and p-y models are developed. • Direct seismic losses and demand capacity ratios are compared for different analysis approaches. • Consideration of site effects simplistically can result in unconservative demands.

Direct seismic loss estimation of predominantly plan‐symmetrical frame buildings using simplified nonlinear models

AbstractThe estimation of building seismic risk and loss utilising response history analysis is challenging, especially because the final objective is the seismic loss estimation for building stock. In this paper, this challenge is addressed by developing a simplified nonlinear structural model, which is capable of simulating the seismic response of predominantly plan‐symmetrical reinforced concrete frame buildings subjected to ground motions in both horizontal directions. The simplified structural model is plugged into the direct seismic risk and loss estimation methodology. Its capabilities are then demonstrated by estimating the seismic risk and losses for a four‐storey office building and a five‐storey school building. For the analysed buildings, it is shown that the frequency of collapse, the expected annual loss and the frequency of exceedance of a given loss can be simulated with the same level of accuracy as in the case of the conventional structural model, but with greater numerical robustness and computational efficiency. Research is needed to better define the limitations of the introduced simplified model and extend the capabilities of simplified nonlinear models to more complex structural systems of plan‐asymmetrical buildings.

Component repair cost functions in Indian context for seismic loss estimation of reinforced concrete buildings

This study proposes component level repair cost functions for efficient estimation of financial losses expected to be incurred due to earthquake-induced damages to typical reinforced concrete (RC) buildings in the Indian context. The proposed repair cost functions account for the variability in the local construction practices and their associated financial implications. Repair cost functions for four drift sensitive building components, i.e., unreinforced masonry walls, reinforced concrete beams, reinforced concrete columns and reinforced concrete beam-column joints, are developed. A detailed case study is presented for three different building configurations commonly observed in the hilly region, i.e., 4-story stepback, 4-story split-foundation, and 4-story regular buildings. The variation in the floor-wise and component-wise repair cost ratio with varying levels of ground motion intensity is investigated. This study also proposes the expected repair cost ratio function for the considered building configurations corresponding to the four building components. It is observed that the expected repair cost ratio is least in 4-story regular building and maximum in 4-story split-foundation building.

The Role of Life Cycle Structural Engineering in the Transition towards a Sustainable Building Renovation: Available Tools and Research Needs

Given the current climate emergency and the ambitious targets of carbon emissions reduction, retrofitting strategies on existing buildings typically include reducing energy demand, decarbonising the power supply, and addressing embodied carbon stored in materials. This latter point redefines the role of engineers in the transitions towards a sustainable construction sector, being they responsible for designing low impact, sustainable and carbon neutral solutions. A Life Cycle Structural Engineering (LCSE) approach, inspired by the principles of Life Cycle Thinking (LCT), should thus be adopted for the sustainable renovation of existing buildings. Only recently have pioneering approaches been proposed, tackling multifaceted buildings’ needs, such as those related to energy consumption as well as seismic safety, but often disregarding LCT principles. This study presents a redefinition of the concept of LCSE for sustainable construction and a comprehensive review of available methods and tools to operationalise the LCSE approach in practice, focusing on the consideration of LCT principles in the retrofitting design process, integration of seismic loss estimation and environmental impact assessment, and implementation of integrated retrofitting strategies. The greatest ambition of this work is thus to boost a paradigm shift for building engineers towards an interdisciplinary perspective in building assessment and retrofitting.